Add Gradle task for building zip with dependencies

Some Spring Framework users and teams cannot use transitive dependency
management tools like Maven, Gradle and Ivy. For them, a `distZip` task
has been added to allow for creating a Spring Framework distribution
from source that includes all optional and required runtime
dependencies for all modules of the framework.

This 'dist-with-deps' zip is not published to the SpringSource
repository nor to the SpringSource community download page. It is
strictly an optional task introduced as a convenience to the users
mentioned above.

Detailed instructions for building this zip locally have been added to
the wiki and the README has been updated with a link to that new doc.

Issue: SPR-6575

README.md

@@ -15,9 +15,9 @@ The framework also serves as the foundation for
 [Python](https://github.com/SpringSource/spring-python) variants are available as well.
 
 ## Downloading artifacts
-Instructions on
-[downloading Spring artifacts](https://github.com/SpringSource/spring-framework/wiki/Downloading-Spring-artifacts)
-via Maven and other build systems are available via the project wiki.
+See [downloading Spring artifacts](https://github.com/SpringSource/spring-framework/wiki/Downloading-Spring-artifacts)
+for Maven repository information. Unable to use Maven or other transitive dependency management tools?
+See [building a distribution with dependencies](https://github.com/SpringSource/spring-framework/wiki/Building-a-distribution-with-dependencies).
 
 ## Documentation
 See the current [Javadoc](http://static.springsource.org/spring-framework/docs/current/api)

build.gradle

@@ -640,7 +640,7 @@ configure(rootProject) {
         description = "Builds -${classifier} archive, containing all jars and docs, " +
                       "suitable for community download page."
 
-        def baseDir = "${project.name}-${project.version}";
+        ext.baseDir = "${project.name}-${project.version}";
 
         from('src/dist') {
             include 'readme.txt'
@@ -671,6 +671,36 @@ configure(rootProject) {
         }
     }
 
+    // Create an distribution that contains all dependencies (required and optional).
+    // Not published by default; only for use when building from source.
+    task depsZip(type: Zip, dependsOn: distZip) { zipTask ->
+        group = 'Distribution'
+        classifier = 'dist-with-deps'
+        description = "Builds -${classifier} archive, containing everything " +
+            "in the -${distZip.classifier} archive plus all runtime dependencies."
+
+        from zipTree(distZip.archivePath)
+
+        gradle.taskGraph.whenReady { taskGraph ->
+            if (taskGraph.hasTask(":${zipTask.name}")) {
+                def projectNames = rootProject.subprojects*.name
+                def artifacts = new HashSet()
+                subprojects.each { subproject ->
+                    subproject.configurations.runtime.resolvedConfiguration.resolvedArtifacts.each { artifact ->
+                        def dependency = artifact.moduleVersion.id
+                        if (!projectNames.contains(dependency.name)) {
+                            artifacts << artifact.file
+                        }
+                    }
+                }
+
+                zipTask.from(artifacts) {
+                    into "${distZip.baseDir}/deps"
+                }
+            }
+        }
+    }
+
     artifacts {
         archives docsZip
         archives schemaZip